Heat exchangers are used to transfer heat from a solid object to a fluid or from one fluid to another fluid. The heat exchanger will include a plurality of elongate tubes that carry steam or water. Over time, solid materials tend to become deposited on the interior surfaces of these tubes and the solid materials may eventually become thick enough to clog the tubes.
It is therefore customary to clean the tubes from time to time. This cleaning is typically accomplished using a water jet to blast away the deposited solid materials. A lance or washer arm having a nozzle at one end is inserted into each tube and a water jet is sprayed out of the nozzle to blast away the clog or blockage.
The nozzles in question typically include a stationary part and a sleeve that rotates about this stationary part. The problem with this cleaning equipment is that because the water is delivered to the nozzle under extremely high pressure, there is a tendency for water to leak out of the top and bottom ends of the rotating sleeve. While the leaking water creates a water bearing that helps the sleeve to rotate, the rate of water leakage in PRIOR ART nozzles may be upwards of about eight gallons per minute. This leakage makes the nozzles far less efficient than desirable and also wastes a considerable amount of water.
The other issue with this cleaning equipment is that as the nozzle comes into contact with deposited material as those deposits are removed from the interior of the tube, some of the particulate materials can become trapped between the rotating sleeve and the stationary part of the nozzle and hinder or even stop the rotation of the sleeve. This can result in damage to the nozzle as water continues to be delivered under high pressure to the nozzle.